CO-Horts

CO-Horts

Monday, November 5, 2018

Why Should You Water Your Trees This Winter

Why Should You Water Your Trees This Winter

Posted by: Andie Wommack, Douglas County Extension

2018 was another dry year for Colorado. 66% of the state is
still experiencing some level of drought, with 37% in either a D3 (Extreme) or
D4 (Exceptional) drought. Agriculture usually feels the effect of drought
during the first year of a really bad drought, but the second year is when
homeowners will start to feel the consequences of our lack of water. If it
looks like we are going to be facing drought conditions again in 2019, you may
experience watering restrictions in your neighborhood if you haven’t already. This could mean that you may not have the water available to play catch-up from not watering during a dry winter season.

Watering your landscape throughout the winter is crucial if
we are not getting moisture. Trees should be watered ten gallons per inch of
trunk diameter at knee height. If we get winter moisture, that amount can be
reduced. Water to a depth of 12 inches since the majority of your tree’s roots
are in the top 6-24 inches of soil. Ideally your trees should be watered three
times in September, and then cut back to once or twice a month October through
March. Water young trees that are not established and evergreens twice monthly
if possible. A tree takes one year for caliper inch of trunk diameter to establish.
If you planted a two-inch tree, you will need to provide extra supplemental
water for two years until it can get established.

Most tree roots extend two to four times the diameter of the
tree’s crown. A storm that produces one inch of rain provides a little less
than 2/3 of a gallon per square foot. A tree with a crown diameter of four feet
would have a root system roughly between eight and sixteen feet. If this tree
has a 12-foot root system, it would receive about 67 gallons of water with one
inch of rain. Keep in mind that one inch of snow does not equal one inch of
rain! According to NOAA, on average, thirteen inches of snow equals one inch of
rain.

Lack of moisture in the months of October through March can
cause damage to the root system of plants which then affects their overall
health. Drought stress will begin to appear in late spring and summer when the
temperatures begin to rise and precipitation amounts decrease. Stressed plants
are also more susceptible to disease and insects.

Make sure that you water on days where the low temperatures
will stay above freezing and the daytime temperatures are above 40 degrees. Water earlier in the day so the water has a chance to soak in to the ground before temperatures decrease at night. Disperse the water evenly around the whole tree underneath the canopy and roughly three feet from the trunk.

Your shrubs will also need extra water! A small established shrub
that is less than three feet needs five gallons every month from October through
March. A large established shrub that is more than six feet needs 18 gallons
monthly. Newly planted shrubs require the same amount of water twice a month. Mulching
is also a great way to retain moisture around your plants! Keep in mind that if
it is dry, your turf will need to be watered as well!